After examining him, Cook invited the boy into his office to talk, and offered to take him out to eat. A week later, they went to dinner and a movie.

It was the first of many gifts.

Cook, 50, bought groceries, clothes, iPods, a Nintendo Wii gaming system and concert tickets for the teen and his family. He quickly became a role model to the boy, whose father lived out of state and was in and out of his life.

"The guy appeared like a knight in shining armor to this family," said Pinellas County sheriff's Detective Jennifer Zinge.

But it wasn't all it seemed.

All the gifts and companionship was a prelude to roughly two years of sexual abuse, authorities say.

Experts call it a classic case of a sexual predator "grooming'' a victim.

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It did not take long for Cook to win over the teenager or his family, authorities say.

Details of the relationship between the teen and Cook, an ER doctor and owner of two Pinellas walk-in clinics, were laid out recently in a search warrant filed in Pinellas County.

Within a month of their first meeting, Cook was spending the night at the teen's home, sleeping next to him in the same bed — something his mother didn't find unusual because she considered Cook a father figure and a role model to the boy.

Cook picked the teen up from high school most days and took him to his clinic. He took him to Walt Disney World for his 15th birthday; they slept in the same bed. They also smoked marijuana and took ecstasy, authorities say.

The teen started calling him "dad" and "pops."

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The first sexual contact occurred on a camping trip to the Appalachian Trail in Georgia.

The teen told a detective he believed Cook was "testing him."

After the trip, Cook rented a house in Safety Harbor. He wanted to be closer to the boy, Cook told him. The teen moved in and the relationship progressed. Cook sexually abused him more than 30 times at that house. He also took nude photos of him and they looked at pornographic websites together.

The sexual interactions continued after Cook became involved with a woman closer to his age and after they both moved into the woman's Dunedin house.

The woman was unaware of what was going on between Cook and the teen, according to court documents. She declined comment for this story.

Cook also rented a motel in Clearwater Beach where the two did LSD together, smoked marijuana and had sex.

In June 2010, Cook's girlfriend told the teen to move out. The boy moved in with family members for six to eight months, seeing little of the doctor.

The teen eventually moved back in with Cook at an Indian Rocks Beach condominium and the sexual interactions continued until February, when the boy broke it off.

Nobody else knew what was going on until the teen confided to a friend, Deputy Zinge said. The friend then contacted law enforcement, prompting an investigation. Cook was arrested Nov. 18 and faces four charges of sexual battery with custodial authority. He is being held without bail.

Lane Lastinger, Cook's attorney, said once the investigation is completed it will be clear that "the allegations contained in the search warrant allegation are greatly exaggerated." He declined to elaborate. Detectives said Cook admitted to the allegations and was cooperative with the investigation.

Cook owns two walk-in clinics in Largo and Clearwater and at the time of his arrest was the director of emergency care at Palms of Pasadena Hospital. He is a former medical director at Morton Plant Hospital's emergency medical facility.

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"Grooming" is common among sexual predators, experts say.

Authorities say Penn State assistant football coach Jerry Sandusky exhibited the behavior, typically approaching boys from troubled or fatherless homes and drawing them in with trips to games and expensive gifts. Touching progressed incrementally, most often becoming overtly sexual in the shower, according to the New York Times.

Sexual predators frequently "groom" to gain the trust of victims and their families, said Dr. Carla van Dam, a clinical and forensic psychologist based in Washington and British Columbia. "It seems like they all went to the same school and learned how to do it," she said.

Such sexual predators typically try to cross a minor boundary, she said. When no one stops them, they take that as a signal that it's safe and they continue, she said. That's just what Cook is accused of doing.

"I think it's a very blatant case of grooming," said Charol Shakeshaft, professor and chairwoman of the Department of Educational Leadership at Virginia Commonwealth University, after reviewing the search warrant.

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Detectives suspect Cook "groomed" two other boys in Florida. In each case, he took them to dinner and movies, bought them gifts, provided their parents with financial support and took them camping along the Appalachian Trail in Georgia, Zinge said.